Psy 123_Lec 6

Highlights basic properties of the visual system

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Unformatted text preview: nderstanding of the visual system. Highlights basic properties of the visual system, outline of what we will be covering today: Transducing Light Energy Into a Neural Signal! In darkness, a rod continuously releases glutamate. ! When light is absorbed by rhodopsin in the outer segment, it breaks down a G-protein and initiates a cascade of chemical events that closes Na+ channels. One photon of light can shut off a million Na+ from entering. This hyperpolarizes the cell. ! The size of the hyperpolarizing potential determines the magnitude of the reduction in the release of neurotransmitters! Rod! The whole visual system tries to enhance the light in particular ways, like enhance lines, contours, so that we can distinguish things apart. Hyperpolarizing the photoreceptor causes them to release less glutamate, which depolarizes the on-center bipolar cell and hyperpolarizes the off-center bipolar cell. Glutamate always depolarizes ganglion cells, so there is increased firing in the on-center ganglion cell and decreased fi...
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This note was uploaded on 01/18/2014 for the course PSY 123 taught by Professor Staff during the Fall '11 term at UCSB.

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